Finding the Fourth Proportional to 1,020.61, 1,408.86 and 772.01

Step by Step Solution

1. Step 1: Write the proportion equation
   1,020.61 : 1,408.86 = 772.01 : x
2. Step 2: Convert to fraction form
   1,020.61/1,408.86 = 772.01/x
3. Step 3: Cross multiply
   1,020.61x = 1,408.86 × 772.01
4. Step 4: Simplify right side
   1,020.61x = 1,087,646.96
5. Step 5: Solve for x
   x = 1,087,646.96/1,020.61
6. Step 6: Final answer
   x = 1,065.69